A method of combining a channel quality estimate for the radio channel based on direct measurement of carrier and interferer energies, and a channel quality estimate for the radio channel based on channel decoder metrics, to obtain a final channel quality estimate in terms of carrier-to-interference (C/I) ratio for the radio channel, which is more reliable, consistent and accurate than that obtained with the individual methods. After computing a direct channel quality estimate and a decoder metric-based channel quality estimate for the radio channel, confidence levels, P(direct), P (metric), are assigned to the two estimates. P(direct) is multiplied with the direct channel quality estimate and P(metric) is multiplied with the decoder metric channel quality estimate. The respective products are added to obtain the final channel quality estimate in terms of the carrier-to-interference (C/I) ratio for the radio channel.
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2. The method of claim 1 further comprising: storing the previous N direct channel quality estimates; and storing the previous N decoder metric-based channel quality estimates.
3. The method of claim 2 wherein P(direct) is a function of the standard deviation σ direct of the previous N direct channel quality estimates, and the standard deviation σ metric of the previous N decoder metric-based channel quality estimates, wherein P(direct) is equal to σ metric /(σ direct +σ metric ).
4. The method of claim 2 wherein P(metric) is a function of the standard deviation σ direct of the previous N direct channel quality estimates, and the standard deviation σ metric of the previous N decoder metric-based channel quality estimates, wherein P(metric) is equal to σ direct /(σ direct +σ metric ).
5. The method of claim 1 wherein P(direct) is set to 0 when C/I(direct) is significantly greater than C/I(metric).
6. The method of claim 1 wherein P(metric) is set to 0 when both C/I(metric) and C/I(direct) are greater than a first threshold.
7. The method of claim 1 wherein the final channel quality estimate is used for adaptive multi-rate (AMR) codec mode adaptation.
9. The system of claim 8 further comprising: means for storing the previous N direct channel quality estimates; and means for storing the previous N decoder metric-based channel quality estimates.
10. The system of claim 9 further comprising means for computing P(direct) as a function of the standard deviation σ direct of the previous N direct channel quality estimates, and the standard deviation σ metric of the previous N decoder metric-based channel quality estimates, wherein P(direct) is equal to σ metric /(σ direct +σ metric ).
11. The system of claim 9 further comprising means for computing P(direct) as a function of the standard deviation σ direct of the previous N direct channel quality estimates, and the standard deviation σ metric of the previous N decoder metric-based channel quality estimates, wherein P(metric) is equal to σ direct /(σ direct +σ metric ).
12. The system of claim 8 further comprising means for setting P(direct) to 0 when C/I(direct) is significantly greater than C/I (metric).
13. The system of claim 8 further comprising means for setting P(metric) to 0 when both C/I(metric) and C/I(direct) are greater than a first threshold.
14. The system of claim 8 wherein the final channel quality estimate is used for adaptive multi-rate (AMR) codec mode adaptation.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 13, 2002
April 25, 2006
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